What is a BMS? It is a cell balancer with some voltage monitors that can stop the flow of electrons.
One of the issues we're facing is there's a number of definitions of BMS. The one you describe serves to protect the battery bank from mis-use. Other systems employ balancing, charge control, reporting/data logging, and other features which can ultimately make the pack as a whole last longer and store and discharge energy more efficiently and safely.
Under your definition, a fuse/breaker can be considered a BMS - it stops the flow of electrons if the voltage gets too high (and pushes/pulls too much current).
Vehicles, as Prowse claims, may exist without typical BMS, however they are fully integrated systems - the motor controller, charger, and other modules all play a part of the BMS role. They are still protected by a BMS, it's just not attached to the battery in a way that it can be used separate from the rest of the vehicle.
If you believe your system, as a whole, can protect the batteries without a standalone BMS, then sure, you could use a pack without a BMS because the system as a whole _does_ manage the battery. You have a BMS, it's just contained in other parts of the system.
If your system does not protect from over/under voltage/current, and doesn't protect against cold charging, then you're going to have a bad day.
If a failure in another part of your system could expose the battery to danger, then you might want to think carefully about whether redundant protection, such as provided by a standalone BMS, would be prudent. It's not just the risk of catastrophic loss, but even minor losses like a runaway cell not being caught in time and at best causing you to lose power while you scratch your head over why the system isn't working, and at worst damage other batteries causing you to lose a lot of money and time to resolve it.
I see videos of youtubers building 16s 280a cells with BMS's. How are they ever going to use the capacity of those systems with a DIY BMS? Why would anyone choose to waste so much power on FET heat?
FETs used in power electronics applications such as this are very low resistance. For instance you can get a $1 FET that supports 287A of current, 60V, with a resistance of 1.2mOhm. So a 16s battery with a 50A load will see a 60mV drop, with 3W heating. If you have a 16s pack of 272A LiFePO4 cells then your total capacity is just shy of 14kWH. Putting a 50A load on it for 5.5 hours will drain it, with the FET losing 3W during that time, or a total of 16.5WH. That results in a total loss of 16.5/13,926 = 0.0012, or 0.12% of your total storage capacity.
$1 and less than 0.2% of your storage capacity is a small price to pay if one of your other system components decides today is a good day to short the solar panels directly to the battery bus, or if a cold snap causes one of the outside edge cells to drop below freezing, causing damage during charging, resulting in a runaway cell you might not notice until it fails months later as it slowly falls out of balance and gets damaged during each cycle.
For my part, if a "BMS" does not measure/report capacity, and does not provide feedback to the charging system about how much current it should be sending, then it's little more than "Battery Protection". And most BMS are only battery protection. Many do provide some limited cell balancing, but without integration with the charger at minimum (as you'll find in vehicles and commercial integrated home systems) it really isn't managing much - merely providing a layer of protection from misuse.